The major goal of this research project is to examine pharmacologic interactions of sympathetic and parasympathetic nervous systems in the anterior segment of the eye. The effects on pupil size, intraocular pressure, and aqueous humor dynamics of agents presumed to act at specific sites in the process of autonomic neurotransmission are first then being examined in eyes to which either sympathetic or parasympathetic input has been systematically elevated or lowered by surgical or pharmacologic means. Basic mechanisms underlying the observed changes in responsiveness will finally be explored with the use of biochemical, physiological, and pharmacological techniques.